Clinical Rule May Cut Use of CT in Kids

Action Points

Note that this prospective cohort study identified clinical factors with a high negative predictive value for intra-abdominal injury among children with blunt abdominal trauma.

Be aware that there was no independent verification cohort; caution should be exercised before implementing this rule in clinical practice.

A seven-item risk-prediction rule identified 95% of youngsters who needed acute interventions for intra-abdominal injuries, suggesting potential for reducing the use of CT and associated radiation exposure, a multicenter study showed.

Based entirely on clinical findings, the rule picked out 197 of 203 children who underwent acute interventions after emergency department assessment, according to a report published online in the Annals of Emergency Medicine.

Of the more than 5,000 patients who had negative abdominal CT scans, the rule correctly excluded intra-abdominal injury in all but six cases.

"Clinicians identified almost all children with intra-abdominal injury undergoing acute intervention because only one patient was discharged home and returned with a missed intra-abdominal injury undergoing acute intervention," James F. Holmes, MD, of the University of California Davis in Sacramento, and co-authors wrote.

"Clinicians, however, frequently obtained abdominal CT scans for children at low risk of intra-abdominal injury undergoing acute intervention, exposing children with very low risk of important injuries to unnecessary radiation risk," they continued. "Those children who have none of the variables in the prediction rule are at very low risk for intra-abdominal injury undergoing acute intervention, and therefore, abdominal CT is generally unwarranted."

Abdominal CT has become standard practice for evaluating children who come to an emergency department with possible abdominal trauma. However, use of CT in trauma and emergency care has grown more quickly than has the evidence to support its use, according to the authors' background information.

CT provides detailed information about injuries but exposes patients to relatively high doses of radiation, which poses a risk of malignancy, according to the authors. With their inherent radiosensitivity, children have an even greater risk of radiation-related malignancy as compared with adults.

Small, single-center studies have suggested that children can be evaluated for intra-abdominal injury by means of readily accessible clinical factors. Holmes and colleagues sought to corroborate those findings in a larger, prospective, multicenter cohort study.

Investigators at 20 member institutions of the Pediatric Emergency Care Applied Research Network enrolled 12,044 children (median age 11.1) who required emergency department evaluation for possible intra-abdominal injury. Emergency physicians collected information related to patient history and physical examination prior to CT scanning (which was performed at the discretion of treating physicians).

During the study the final decision regarding CT findings and intra-abdominal injury rested with participating physicians or board-certified radiologists. Indeterminate results were adjudicated by a separate review.

Treating physicians decided whether patients should be hospitalized. The disposition of each patient was determined by telephone at least 7 days after the emergency department visit and by mail for patients who could not be contacted by phone.

To develop the risk-prediction rule, the investigators used validated software for clinical decision making. They input a variety of variables and patient characteristics identified in published literature or that had biologic or physiologic plausibility as a contributing factor to intra-abdominal injuries. Factors were excluded if pertinent data were missing from 5% or more of patient records or if inter-observer variability was too great.

The primary outcome was intra-abdominal injury requiring acute intervention. The results showed that 5,514 (46%) of the patients underwent abdominal CT in the emergency department, during hospitalization, or after discharge.

Overall, 761 patients (6.3%) had diagnoses of intra-abdominal injury, including 204 who had injuries to more than one organ. There were confirmed intra-abdominal injuries in 203 patients (26.7%), including 191 who had abdominal CT in the emergency department.

Analysis of factors associated with intra-abdominal injury led to a prediction rule that included seven of the factors. In descending order of predictive value, they were:

Evidence of abdominal trauma or seat-belt sign

Glasgow Coma Score <14

Abdominal tenderness

Evidence of thoracic wall trauma

Complaints of abdominal pain

Decreased breath sounds

Vomiting

The resulting rule had a negative predictive value of 99.9%, sensitivity of 97%, specificity of 42.5%, and negative likelihood ratio of 0.07.

On the basis of the risk-prediction rule, almost a fourth of abdominal CT scans were performed in very-low-risk patients.

"This suggests that there is substantial potential for reducing unnecessary abdominal CT scanning in children after blunt torso trauma because the purpose of the current prediction rule was to identify low-risk children in whom CT could generally be obviated," the authors wrote in their discussion.

"The rule is not intended to suggest that all those who screen positive for one or more rule variables must undergo abdominal CT scanning," they added. "Such a practice would increase the rate of abdominal CT scanning and is not recommended. Ultimately, the rule helps match the risk of radiation with the risk of intra-abdominal injury in that CT scan use should be minimized in patients who are at very low risk by the prediction rule."

The authors pointed out that the prediction rule requires external validation before use in clinical practice.

The study was supported by the Centers for Disease Control and Prevention.

The authors had no relevant disclosures.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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